Patent Application
20130168102
This invention relates in general to offshore well riser adapters and, in particular, to a riser adapter for connecting to subsea equipment with subsea functionality.
In offshore drilling operations, the operator will perform drilling operations through a drilling riser. The drilling riser extends between the subsea wellhead assembly at the seafloor and the drilling vessel. The drilling riser is made up of a number of individual joints or sections. These sections are secured to each other and run from a riser deploying floor of the drilling vessel. The drilling riser also normally has a number of auxiliary conduits that extend around the main central pipe. Some of the auxiliary conduits supply hydraulic fluid pressure to the subsea blowout preventer (BOP) and lower marine riser package (LMRP). Further, some of the auxiliary conduits provide well choking, killing, and drilling mud adjustments. The LMRP attaches to the BOP and the LMRP that allows quick disconnection from the BOP in the event of an emergency. The BOP may also remain attached to the LMRP. Typically, the BOP has two redundant subsea control modules having electrical and hydraulic components for controlling the BOP and LMRP. Further, the auxiliary conduits may also provide well choking, killing, and drilling mud adjustments. Each subsea control module is fairly large and complex as they control many different functions, such as the various rams and closure elements, connectors and the like of the BOP. If a problem is detected, one of the subsea control modules may be retrieved, usually on a lift line, while the other maintains operation of the BOP.
The lower end of the drilling riser typically has an adapter that couples to the LMRP for connecting the riser to the LMRP. Various adapters have been employed. The adapter connections typically include bolted flanges, locking segments radially moveable by screws, or cam rings. The BOP couples by a hydraulic connector to a subsea wellhead assembly at the sea floor. The LMRP also includes an emergency disconnect to quickly release from the BOP. The various hydraulically driven components of the LMRP are supplied with hydraulic fluid and controlled by lines leading to the surface vessel.
The BOP and adapter serve to provide choke-and-kill functionality in the event that control of the well is lost. Environmental impact from an uncontrolled well is lessened when the components function correctly. However, in some emergency situations, escaping oil from an uncontrolled well may require capacity for directing the escaping oil to a containment vessel or other location. Further, functions such as dispersant injection, mud circulation, mud booster, top killing, and dual gradient drilling can be accommodated.
These and other problems are generally solved or circumvented, and technical advantages are generally achieved, by preferred embodiments of the present invention that provide a drilling riser adapter with subsea functionality, and a method for using the same.
An embodiment of the present invention provides a system for connecting a lower marine riser package (LMRP) and BOP to a marine riser. The LMRP and BOP will be placed subsea at a wellhead so that the riser will extend from the wellhead to a drilling rig located at a sea surface. The system comprises a drilling riser joint. In one embodiment, the drilling riser joint is a drilling riser adapter that has a mating flange on upper and lower ends to mate with riser and LMRP, respectively.
The drilling riser adapter may have a cylindrical body with a bore with the riser adapter having means for mounting to the LMRP, such as a mating flange. The drilling riser adapter may also engage a lower end of the marine riser with a mating flange. Further, a plurality of ports are disposed circumferentially on the body of the riser adapter, with the ports adapted for receiving connections to facilitate ingress or egress of fluid to and from the wellbore through the sidewalls of the drilling riser adapter.
During an emergency, umbilicals or flexible hoses can be connected to the ports via an ROV. For example, the ports can be configured to connect to either hard lines or flexible hoses to perform mud circulation, chemical injection, escaping fluid collection, or a top-kill operation. These operations can also connect to the riser adapter mating flange on the upper end of the riser adapter via inlets formed on the mating flange. Fluids can then be pumped down the respective lines depending on the operation. Further, at least one of the plurality of ports can be selectively activated or deactivated in response to well conditions such as escaping oil due to oil spill. As previously explained, ports may also facilitate functions such as mud circulation, chemical injection, or top-kill operations.
So that the manner in which the features, advantages and objects of the invention, as well as others which will become apparent, are attained, and can be understood in more detail, more particular description of the invention briefly summarized above may be had by reference to the embodiments thereof which are illustrated in the appended drawings that form a part of this specification. It is to be noted, however, that the drawings illustrate only a preferred embodiment of the invention and are therefore not to be considered limiting of the invention's scope as the invention may admit to other equally effective embodiments.
The present invention will now be described more fully hereinafter with reference to the accompanying drawings which illustrate embodiments of the invention. This invention may, however, be embodied in many different forms and should not be construed as limited to the illustrated embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout, and the prime notation, if used, indicates similar elements in alternative embodiments. The use of “first”, “second”, “upper”, “below”, and similar descriptive language is only meant to more easily identify parts in figures and not as limitations.
In the following discussion, numerous specific details are set forth to provide a thorough understanding of the present invention. However, it will be obvious to those skilled in the art that the present invention may be practiced without such specific details. Additionally, for the most part, details concerning drilling operations, rig operations, general riser make up and break out, and the like have been omitted inasmuch as such details are not considered necessary to obtain a complete understanding of the present invention, and are considered to be within the skills of persons skilled in the relevant art.
Referring to
Normally subsea equipment, such as the LMRP 17, a subsea tree, or BOP 14, will have receptacles for a number of subsea control modules, and many of the control modules will differ from each other because of the different functions that they are intended to perform. The BOP 14 may be connected to the LMRP 17 in certain cases and may be provided with a mechanism to allow quick disconnection of the LMRP 17 from the BOP in the event of an emergency.
Continuing to refer to
Referring to
Continuing to refer to
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A booster inlet 60 can be formed on upper mating flange 34 of riser adapter 16. Booster inlet 60 extends downward through flange 34 of adapter 16 and connects to booster line 22 to allow fluid communication with booster reentry port 62. Booster reentry port 62 is in communication with bore 32 of riser adapter. Booster reentry port 62 extends downward about the same distance as choke/kill outlet 44 although the downward extension of reentry port 62 may vary when compared to the choke/kill outlet 44. Booster reentry port 62, which is in fluid communication with bore 32, allows for injecting an additional flow of mud from booster line 22 to bottom of riser string 10 to facilitate the return of the cuttings from drilling operations and also allows for adjustment of drilling mud properties, such as density, to meet drilling requirements. As shown in
Although booster reentry port 62 is shown reentering bore 32 at an axial mid-length of riser adapter 16, the booster reentry port could be formed at other points in the riser adapter.
Continuing to refer to
Ports 70, 80, 90, 94 will typically be dormant, with valves 72, 82, 92, 96 in a closed position. In this embodiment, flexible hoses will typically not be connected to ports 70, 80, 90, 94. However, upon a need to perform an operation, umbilicals from the floating vessel such as hoses 100, 102, could be connected, for example, to first port 70 and second port 80. Valves 72 and 82 could be actuated to open. Hoses 100 and 102 can be flown and connected to ports 70 and 80 on riser adapter 16 by an ROV 47 that has facilities for carrying, installing, and flying umbilicals to riser adapter 16 and can be controlled remotely from a floating vessel 12 (shown in
Although hoses 100 and 102 are shown connected to ports 70 and 80, any combination of ports 70, 80, 90, and 94 could be used. Depending on the function, the opposite ends of hoses 100 and 102 may be routed to sources or terminations either at the surface vessel or the seabed. For example, in the event that the well becomes uncontrolled, it is possible that oil could escape, posing an environmental risk. In this type of emergency situation, ROV 47 could be deployed with a hose, such as hose 100, and flown to the riser adapter 16 for connection of the hose with one of the ports, such as first port 70. An opposite end of hose 100 could be connected to a containment vessel (not shown) such as an oil tanker or other facility. Because port 70 is in communication with the wellbore via bore 32 of adapter 16 and the bore of the riser string 10, the escaping oil flowing up BOP 14 into adapter 16 can be routed to the relative safety of containment vessel via hose 100 for additional processing, such as burning. Valve 72 can be actuated to open via BOP panel 76 to activate port 70 and thus allow flow of oil to the containment vessel. If additional oil removal capacity is needed, ROV 47 can install additional hoses, such hose 102 and 104 on additional ports 80, 90, and 94. Like hose 100, the additional hoses can also be routed to the containment vessel. To facilitate flow of oil through the ports, a plug can be inserted into the upper end bore 32 of riser adapter 16 above ports 70, 80, 90, and 94 to force oil into the ports and thus hoses. Suction pumps may also be employed to increase flow to containment vessel. It is understood that additional ports could be added to riser adapter 16 to provide additional oil removal capacity or other functionality. Hoses may also be connected to ports prior to any event occurring that would require their use.
In an additional embodiment shown in
The embodiment shown in
The invention described above provides several advantages due to its multi-functionality. Drilling operators can use this improved riser adapter with multiple ports to top kill wells, and perform dual gradient drilling, dispersant injection, mud recirculation, and mud boosting functions. Replacing auxiliary lines of a riser for booster, choke/kill, and hydraulic function with flexible hoses that can be directed to connection on the flange of the riser adapter also eliminates the necessity of hard lined auxiliary lines on the drilling riser. This replacement of auxiliary lines can be carried out during emergencies or on a permanent basis, however, the option to continue using the hard lined auxiliary lines is still available if desired or required by a project. Further, the riser adapter can be retrofitted into existing risers by designing it so that any riser flange types and sizes. This modified riser adapter is a single device that can be used for ordinary drilling operations while its emergency functions remain latent until or if needed. These emergency functions thus remain non-intrusive while inactive and potentially increase safety and potentially reduce the potential risk of environmental impact when activated.
During operation, the riser could be disconnected from the LMRP. The riser adapter may be plugged and may remain on the LMRP. If an emergency situation occurs such that the well becomes uncontrolled, hoses may then be connected to ports on the riser adapter, as previously described, to divert oil to containment vessels.
It is understood that the present invention may take many forms and embodiments. Accordingly, several variations may be made in the foregoing without departing from the spirit or scope of the invention. Having thus described the present invention by reference to certain of its preferred embodiments, it is noted that the embodiments disclosed are illustrative rather than limiting in nature and that a wide range of variations, modifications, changes, and substitutions are contemplated in the foregoing disclosure and, in some instances, some features of the present invention may be employed without a corresponding use of the other features. Many such variations and modifications may be considered obvious and desirable by those skilled in the art based upon a review of the foregoing description of preferred embodiments. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the invention.
